Hard surfacing alloy



United States Patent Ill., a corporation of Illinois No Drawing. FiledJuly 26, 1962, Ser. No. 212,717 3 Claims. (Cl. 75-123) The presentinvention relates to hard surfacing alloys of the cast iron type forproviding hard facing on metals by welding techniques.

Previously proposed hard facing compositions of the cast iron type werefrequently satisfactory from the standpoint of hardness, tensilestrength, and yield strength, but they frequently lacked adequateresistance to abrasion and, in some instances, suffered excessivereduction in their strength properties upon being heated to elevatedtemperatures.

The present invention provides an'improved hard surfacing alloycomposition which can be used in the form of a welding electrode orwelding rod and which overcomes the deficiencies of hard surfacingcompositions heretofore produced. The compositions of the presentinvention, when applied as hard facings, exhibit excellent hardnessproperties, and resistance to abrasion. They are also capable ofretaining, to a substantial degree, their improved physical propertiesat intermediately high operating temperatures.

The alloy compositions of the present invention are cast irons whichcontain nickel, molybdenum, tungsten, silicon, and manganese incontrolled amounts to provide the desirable strength and hardnessproperties while in addition providing excellent resistance to abrasivewear.

An object of the present invention is to provide an improved hard facingmaterial for application by electrical or gas welding.

A further object of the invention is to provide a hard facing alloywhich When applied to a metal substrate exhibits excellent hardness andresistance to abrasion.

A further object of the invention is to provide an improved hard facingalloy which retains its improved physical properties even atintermediately high operating temperatures.

The improved hard facing material of the present invention has ananalysis within the following ranges:

Percent Silicon 1.50 to 2.50 Manganese 0.50 to 1.00 Total carbon 2.50 to3.50 Phosphorus 0.055 to 0.200 Sulfur 0.040 to 0.150 Nickel 2.00 to 4.00Molybdenum 0.30 to 1.00 Tungsten 0.75 to 2.00

Iron, substantially the balance.

The improved physical properties of the alloys of the present inventionare believed due, at least in part, to the proper correlation betweenthe hardness imparting ingredients which include the nickel, molybdenum,tungsten, and manganese. For example, the particularly preferred a1-loys, according to the present invention, are those in which the nickelcontent ranges from about 2.0 to 4.0%, and in which the nickel tomolybdenum ratio is about 4 to 3,243,286 Patented Mar. 29, 1966 to 1,the nickel to tungsten ratio is about 2 to 5 to l, and the nickel tomanganese ratio is about 3 to 6 to l.

A particularly preferred alloy, coming within the scope of the presentinvention, has the following analysis:

Percent Silicon 2.07 Manganese 0.6 Total carbon 3.0 Phosphorus 0.075Sulfur 0.05 Nickel 3.0 Molybdenum 0.5 Tungsten 1.5 Iron, substantiallythe balance.

The hard facing compositions of the present invention can be used eitheras welding rods in normal gas type welding, or as electrodes forelectrical welding. For the latter use, it is desirable to employ thecomposition in the form of a rod having a mineral surface coating or thelike.

In the as cast condition, the hard facing materials of the presentinvention evidenced areas of acicular graphite formation and some areasof cementite. When applied as a hard facing to a substrate, the depositis characterized by the presence of martensite, austenite, andcementite, each of the constituents comprising roughly 10 to 50% of thetotal.

Tests made on the improved facing alloys of the present inventionindicate that they are at least equivalent in physical properties toother hard facing compositions of the cast iron type, and havesubstantially improved abrasion resistance. For example, the tensilestrength of the alloy is normally in the range from 40,000 p.s.i. to55,000 pounds per square inch. The mechanical properties of a 1.2 inchdiameter bar evidence transverse rupture stress in the range from about3,000 to 5,000 pounds per square inch. The Brinell on a 1.2 inchdiameter bar ranges from 250 to 300 B.H.N. hardness when applied as afacing ranges from about 350 to 600 since the material is workhardenable.

From the foregoing, it will be evident that the hard facing compositionsof the present invention provide an improved material for application tosurfaces which require a coating of a hard facing material for abrasionresistance. It will also be evident that various modifications can bemade to the described embodiments without departing from the scope ofthe present invention.

I claim as my invention:

1. A cast iron Welding rod having improved resistance to abrasion andconsisting essentially of the following:

Iron, substantially the balance.

2. A cast iron welding rod having improved resistance to abrasion 'andconsisting essentially of the following:

Iron, substantially the balance said rod in the as cast conditionevidencing areas of acicular graphite formation and some areas ofcementite. 3. A cast iron welding rod having improved resistance toabrasion and consisting essentially of the following:

Percent Silicon 1.50 to 2.50 Manganese 0.50 to 1.00 Total carbon 2.50 to3.50 Phosphorus 0.055 to 0.200 Sulfur 0.040 to 0.150 Nickel 2.00 to 4.00Molybdenum 0.30 to 1.00 Tungsten 0.75 to 2.00

Iron, substantially the balance said rod in the as cast conditionevidencing areas of acicular graphite formation and some areas ofcementite,

and when deposited as a facing, the facing being characterized by thepresence of areas of martensite, austenite, and cementite.

References Cited by the Examiner UNITED STATES PATENTS 1,166,342 12/1915Field et a1. 75123 1,803,634 5/1931 Morgan 148--24 1,944,178 1/1934Hornerberg 75124 X 1,999,888 4/1935 Ammann 75l23 X 2,145,757 1/1939Ervin 75123 X 2,165,022 7/1939 Anderson 75--123 X 2,184,518 12/1939 Eashet al. 75-124 X 2,266,762 12/ 1941 Jerabek 75123 X 2,485,761 10/1949Millis et a1. 75123 X 2,507,195 5/1950 Colbeck'et al 75-123 2,516,5247/1950 Millis 75-123 2/1957 Borneman et a1. 75123 X OTHER REFERENCES ILi & Wang, Tungsten, Reinhold Publ. Corp., 2nd edition, 1947, pages 330,333-334.

The Metals Handbook, article on page 722 (1948 edition).

DAVID L. RECK, Primary Examiner.

HYLAND BIZOT, Examiner.

N. F. MARKVA, P. WEINSTEIN, Assistant Examiners.

1. A CAST IRON WELDING ROD HAVING IMPROVED RESISTANCE TO ABRASION ANDCONSISTING ESSENTIALLY OF THE FOLLOWING: